Operation of electrical condensers



March 17, 1936. E. J. H. BussARD Z OPERATION OF ELECTRICAL CONDENSERS Filed Nov. 21, 1954 I INVENTOR. EMMEEY :1 hi Buss/v Ra.

ATTORNEYS.

Patented Mar. 17, 1936 UNITED OPERATION OF ELEQTRECAL CONDENSERS Applicatien November 21, 1934, Serial No. 754,045

8 Claims.

My invention relates primarily to the operation of electrical condensers or condenser gangs, such as those in radio receiving sets. It is common practice to employ Vernier drive means for condenser shafts, and it has likewise been suggested to employ various types of speed reducing mechanisms having primary and secondary shafts on a common axis. Some difficulty has been had with the latter type of mechanism in that there is likely to be slippage between the condenser shaft as such and a dial or other indicating means, which, mechanically at least, is supposed to indicate the rotary position of the condenser shaft, and especially for this reason it has not been found practicable to combine the two types of drives hereinabove mentioned.

The primary objects of my invention are the solution of these and other problems connected with the provision of a positively indicating structure, which nevertheless has a high ratio speed reducing drive, and these objects will be referred to hereinafter or will be apparent to one skilled in the art upon reading the ensuing specifications. In these modifications I shall describe one form of my invention as an exemplary embodiment, it being understood that this embodiment is not a limitation thereon.

Reference may now be made to the drawing, wherein Fig. 1 is a front view of an exemplary panel of a radio set.

Fig. 2 is an elevational view of a condenser structure with parts of the panel of Fig. 1 shown in section.

Fig. 3 is a sectional view of the drive taken along the lines 3, 3 in Fig. 2.

Fig. 4 is a sectional view of a speed reducing device which I may use, taken along the lines 4, 4 in Fig. 3.

In the figures, I have shown a condenser having a main frame I, and rotor and stator combinations indicated broadly at 2. The rotor blades of the individual condensers of the gang will be fastened to a main shaft 5. There is a supplementary shaft member in the form of a sleeve 6, which is preferably substantially co -axial with the main shaft 5, but has a driving connection therewith which involves reduction of speed. A number of such driving connections may be employed, such as ears, friction members, eccentric frictional drives and the like. Supplementary shaft 6 has a disc 1 attached thereto by means of a collar 8. A Vernier drive mechanism actuates the disc I, and in an exemplary form may comprise a shaft 9 suitably journaled as at main shaft 5 comprises a ball bearing frictional driving means. The end of the shaft 5 is elongated to form a sleeve it, within which the supplementary shaft member 5 fits. The sleeve 53 is perforated as at is to accept a series of balls i5, which engage the shaft 5. This shaft may be grooved at the point of engagement, as shown at 65 in Fig. i. outwardly of the shaft extension l3 the balls engage a race-way H, which may be formed in the frame member i of the gang condenser if desired, or may be provided by a separate piece. In the exemplary embodiment shown this race-way acts as a thrust bearing, and a cooperating thrust bearing for the other end of the shaft 5 is indicated at l8, where I have shown a single ball fitting into a socket in the rear frame member of the gang condenser. It will be clear that as the supplementary shaft 6 is turned, the motion transmitted thereby to the main shaft 5 will be diminished. As the shaft 6 turns, it rotates the balls l5 against the race-way l1, tending to cause these balls to move around the race-way. As they move around the race-way they carry with them the shaft 5 by reason of the fact that they press against the sides of the perforations l4 in the sleeve I 3. By properly proportioning the size of the members, the ratio of motion of shaft 8 to shaft 5 may be varied. I have secured excellent results with a ratio of motion of about five to one.

It will be clear from a consideration of the parts heretofore described that as the shaft 9 is rotated by means of the knob iii, the disc 1 will be rotated, but at a very much lower speed. By way of example but without limitation, it may take ten rotations of the shaft 9 to rotate the disc 1 once. This ratio of motion is, of course, multiplied by the speed reducing connection between shaft 6 and shaft 5, as will be obvious.

It will be equally clear, however, that it would not be particularly advantageous to mount an indicating device, whether a dial or a pointer, in connection with the disc 1 or shaft 5 for the reason that slippage is quite likely to occur between shaft 6 and shaft 5. Indeed, even if a positive gear train were used between shaft 6 and shaft 5, there is still the possibility of some of the collars becoming loosened and slippage occurring, either in the gear train or between shaft 6 and disc I. The ultimate end of the desired type of indication is, of course, the actual position of shaft 5. I have overcome this difficulty by attaching my indicating device to shaft 5 in such a Way that it must move exactly with it at all times. In the specific embodiment which I have shown, I accomplish this end by providing a stud like shaft member I9, which passes through a hole in the supplementary shaft 6 and is positively attached to the shaft 5, as at 20.

Any form of attachment which is convenient may be employed. I prefer toknurl the end of the stud l9 and form a driving fit thereof with a perforation centrally of the main shaft '5. The stud [9 can act as a bearing for the supplementary shaft 6 in the particular embodiment illustrated. The stud projects beyond the shaft 6 and is adapted for the attachment of a suitable indicating device. This indicating device may be in the form of a dial or of a pointer, or any other suitable indicating means of which many have been suggested. In the particular embodiment I have shown a pointer 2| attached to the stud by means of a nut 22 on the threaded end thereof, there being a lock nut 23 on the stud behind the pointer. The pointer moves over a scale indicated at 24, suitably supported as at 25. The scale, of course, may be of translucent substance and may be illuminated from the rear. I have shown a type of dial having an upper half for tuning on one wave length, and a lower half for tuning on another wave length. The pointer 2| therefore is a double ended pointer. It will be appreciated that especially for modern superheter'odyne receiving sets and for receivers using a single dial for a plurality of wave bands, extremely close and accurate tuning is highly desirable. Hence the need for a great ratio of speed between an operating knob, such as the knob l2, and the shaft of the condenser. A very great ratio of speed is obtained by a. device such as I have described, with a minimum of space requirement, which is one of its primary advantages. 'An equally important advantage of my structure is, however, that slip motion driving meansmay be employed without in any way destroying the positiveness of the indication given of the position of the condenser shaft.

Modifications may be made in my invention without departing from the spirit thereof.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In speed reduction driving and indicating mechanism, the combination of a main driven shaft, a member having a speed reducing driving connection thereto and being substantially co-axial therewith, and a member positively secured to said driven shaft, extending through said last mentioned member, and hearing at its outer end indicating means.

2. In speed reduction driving and indicating mechanism, the combination of a main driven shaft, a member having a speed reducing driving connection thereto and being substantially co-axial therewith, a member positively secured to said driven shaft, extending through said last mentioned member, and bearing at its outer end indicating means, driving means, and a speed reducing connection between said driving means and said co-axial member.

3. In a speed reduction driving and indicating mechanism, a main driven shaft, an extension on said shaft bearing indicating means, a sleeve on said extension, a speed reducing operative connection between said sleeve and said shaft, a disc mounted on saidsleeve, and Vernier driving means for said disc.

4. In combination, a condenser having a frame and a main shaft, a sleeve member substantially co-axial with said main shaft, a speed reducing driving connection between said sleeve member and said shaft, and a member affixed to said shaft and extending through said sleeve, said member bearing indicating means.

5. In combination, a condenser having a frame and a main shaft, the end of said shaft forming a sleeve, a supplementary sleeve member within said first mentioned sleeve, said first mentioned sleeve being perforated, frictional driving means passing through said perforations and contacting said second sleeve, an outer race-Way for said frictional driving members, a stud passing through said supplementary sleeve and extending therebeyond, said stud being fastened to said main shaft, and indicating means on the free end of said stud.

6. In combination, a condenser having a frame and a main shaft, the end of said shaft forming a sleeve, a supplementary sleeve member within said first mentioned sleeve, said first mentioned sleeve being perforated, frictional driving means passing through said perforations and contacting said second sleeve, anouter race-way for said frictional driving members, a stud passing through said supplementary sleeve and extending therebeyond, said stud being fastened. to said main shaft, and indicating means on the free end of said stud, a disc fastened to said supplementary sleeve, and Vernier driving means for said disc. I

7. In combination, a condenser having a frame and a main shaft, the end of said shaft forming a sleeve, a supplementary sleeve member within said first mentioned sleeve, said first mentioned sleeve being perforated, frictional driving means passing through said perforations and contacting said second sleeve, an outer race-way forsaid frictional driving members, a stud passing through said supplementary sleeve and extending therebeyond, said stud being fastened to said main shaft, indicating means on the free end of said stud,a disc fastened to said supplementary sleeve, Vernier driving means for said disc, said indicating means comprising a pointer aifixed to said stud, and a dial over which said pointer moves. V

8. In a reduction speed driving and indicating mechanism, the combination of a main driven shaft and a plurality of speed reducing driving mechanisms therefor connected in series, at least one of said driving mechanisms lying in front of said driven shaft, and a member positively affixed to said driven shaft and extending through said front-lying mechanism, said member bearing indicating means. I

EMMERY J. H. BUSSARD..

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